Japanese unexamined patent application publication No. JP-A-2001-134080 (Patent Document 1) describes a related art image forming apparatus. For instance, a laser beam printer described as an electrophotographic image forming apparatus in Patent Document 1 is equipped with a developing device that develops an electrostatic latent image produced on a photosensitive drum into a visible toner image. The developing device has a case that stores toner and has an opening formed therein and a developing roller that is rotatably supported by the case so as to face the opening and that supplies toner to the photosensitive drum.
The developing device has a developing agent leakage prevention member for preventing leakage of toner from both ends of a developing roller. The developing agent leakage prevention member includes a side seal layer made of sponge and a fluorine-based felt layer. The side seal is attached to side seal attachment areas opposing respective longitudinal ends of the developing roller in the case by means of a double-sided tape so as to curve along an outer circumferential surface of the developing roller. In this state, the fluorine-based felt is attached to the side seals by means of the double-sided tape, to thus curve as do the side seals. The side seals form base portions of the developing agent leakage prevention member.
In such a developing agent leakage prevention member, the fluorine-based felt remains in close contact with both ends of the outer circumferential surfaces of the developing roller by means of elasticity of the side seals. Therefore, since the fluorine-based felt comes into slidable contact with both ends of the outer circumferential surface of the rotating developing roller, leakage of toner from both ends of the developing roller is prevented.